1. Field of the Invention
The present invention relates generally to the field of power trains and more particularly to a decoupling arrangement between a drive source and a power train.
2. Description of the Related Art
Various arrangements are known for driving a power train from a drive source that provide for decoupling of the power train from the drive source. For example, such arrangements are disclosed in U.S. Pat. Nos. 3,508,179, 4,107,486, 4,190,755 and 4,351,994, and Moto-Draulic switch operator illustrated in S&C Electric Company Photo Sheet No. 740-4.1 (Sept. 23, 1968), the Delta-Star switch operating mechanism illustrated in the H. K. Porter Catalog, reference Catalog No. 1-160 (April, 1971), the MO-10 Motor Operator illustrated in the I-T-E Imperial Corporation Catalog Section 13.4.1.1-13.4.1.2 (Aug. 30, 1968), and the CM-4A motor operating mechanism illustrated in Siemens-Allis Brochure DS4.2 (June, 1983).
As illustrated in FIG. 1 of U.S. Pat. No. 3,508,179, a switch drive shaft 29 of the power train is connected by a shaft coupler and bearing assembly indicated generally at 30 to a switch operating mechanism indicated generally at 31. Specifically, a selector handle 38 (FIGS. 1, 2 and 12) operates a clutch 45 (FIG. 2) to disconnect the shaft extension 43 (FIGS. 2 and 5) of the switch drive shaft (power train) 29 from the output shaft 48 (FIG. 5) of the drive source. As seen in FIG. 5 of that patent, the lower end of the shaft extension 43 receives a clutch-driven member 44. A transverse slot 46 is provided in the lower end of the clutch-driven member 44 for receiving a coupling bar 47 that is secured to the upper end of the output shaft 48. The switch drive shaft 29 of the power train is capable of being recoupled to the switch operating mechanism 31 in only one position of annular alignment of the transverse slot 46 and the coupling bar 47 as shown by indicators operated individually from the switch drive shaft and the motor of the drive source. The arrangement in U.S. Pat. No. 4,107,486 is similar to that of U.S. Pat. No. 3,508,179. As seen in FIG. 19 of U.S. Pat. No. 4,107,486, a coupling 74 includes a slot 78 for receiving a coupling bar 80 on the end of a shaft 82. Similarly to U.S. Pat. No. 3,508,179, the coupling/decoupling arrangement is operable via the selector handle 38. Additionally, operation of the selector handle 38 to the decoupled position also locks the switch drive shaft of the power train. The motor of the drive source is held inoperable while the switch drive shaft is being decoupled and locked.
U.S. Pat. No. 4,190,755 provides for the uncoupling of a switch operating mechanism from the drive linkage or power train of a switch as the switch operating mechanism is withdrawn from an enclosure. Referring to FIGS. 2 and 8 of that patent, a coupling member 106 is fixedly carried by a drive shaft 108 of the drive linkage (power train) 30 of the switch. The switch operating mechanism includes an output shaft 115 that carries an output coupling member 114. The output coupling member 114 rigidly carries a coupling pin 116. The coupling pin 116 is received within two notches 105 and 107 of the coupling member 106 when the switch operating mechanism is inserted to the coupled position. Upon rotation of the output shaft 115, the drive linkage 30 is driven by engagement of the coupling pin 116 in the notches 105 and 107 of the coupling member 106. When the switch operating mechanism is uncoupled from the drive linkage 30, movement of the switch is inhibited by a locking mechanism.
Considering U.S. Pat. No. 4,351,994, a decoupling arrangement is provided for switchgear as shown in FIGS. 1, 15 and 16B of that patent to decouple the operating mechanism from the switch. Specifically, a coupling bolt 578 is carried by strut-driving shaft 568 via threaded engagement of the coupling bolt 578 in a threaded hole 584 formed through the strut-driving shaft 568. The coupling bolt 578 includes a conical head 580. In the coupled position, the conical head 580 is firmly maintained within a hole 576 of a drive lever 200. The coupling bolt 578 includes a blind bore containing a spring-biased plunger 636. The coupling bolt 578 is accessible for engagement by a tool 653 through a compartment 652. The tool 653 is inserted to depress the plunger 636 and to rotate the coupling bolt 578. To accomplish decoupling, rotation of the coupling bolt 578 via the tool 653 in one direction moves the coupling bolt 578 away from the drive lever 200 with the conical head 580 being withdrawn from the tapered hole 576 of the drive lever 200. The strut-driving shaft 568 is locked upon withdrawal of the coupling bolt 578 to prevent movement of the switch blades. Decoupling is prevented except when the switch is in either the fully-open or fully-closed position. For this purpose, holes 664 and 666 (FIGS. 15 and 17A) are located in a back plate 658 for passage of the tool 653 such that the coupling bolt 578 is aligned with one of the respective holes 664,666 for access by the tool 653 when the switch is in one of the corresponding fully-open or fully-closed positions. The Moto-Draulic switch operator is similar to the arrangement in U.S. Pat. No. 4,351,994 and includes a clutch screw that is carried by a crank of the power train. The clutch screw is moved into and out of engagement with a driving arm connected to the drive source to accomplish coupling and decoupling. Upon withdrawal of the clutch screw to accomplish decoupling, the clutch screw is received within a hole to lock the power train against movement. l
The Delta-Star switch operating mechanism includes a hollow coupling member carried by the power train that is slidably moved over an extending shaft from the drive source of the operating mechanism. The extending shaft includes a protruding member that interfits within a receiving portion extending from the hollow coupling member to provide coupling of the extending shaft and the power train. The receiving portion extends radially from the hollow coupling member and the protruding member extends radially from the extending shaft. A locking plate is provided to define an alignment surface such that the hollow coupling member can be retained in a decoupled position only when the hollow coupling member is at a predetermined rotary position so as to align an extending flange with the locking plate. When the hollow coupling member has been decoupled and raised to bring the extending flange above the locking plate, the shackle of a lock is placed through holes in the extending flange of the hollow coupling member to lock the power train in the decoupled position.
The I-T-E MO-10 motor operator includes a coupling assembly (FIG. 2) to provide decoupling of a fixed coupling driven by the drive source from a pipe coupling carried by the power train. The two couplings are joined by a latch bar (uncoupling bar in FIG. 2) that is pivotally carried by the pipe coupling. The latch bar in the coupled position is positioned into a notch provided on the fixed coupling so that rotation of the fixed coupling is imparted to the pipe coupling via the latch bar. The latch bar is pinned in the coupling position via insertion of a pin through holes in the pipe coupling and the latch bar. A padlock is inserted through the pin. To accomplish decoupling, the pin is removed and the latch bar is disengaged from the fixed coupling. The latch bar is pivoted through an open or closed indicator member and retained by insertion of the pin through the latch bar. The shackle of a padlock is inserted through the pin.
The CM-4A motor operating mechanism in FIGS. 7 and 8 of the DS4.2 brochure provides for decoupling of the switch from the motor operator by the pivoting of a lever carried on the power train. In the coupled position, a pin carried by the lever engages a slot that is milled off center in the vertical output shaft. When the lever is pivoted to accomplish decoupling, the pin is lifted out of the slot. The lever is pivoted by insertion of a pipe in a socket that is provided on the lever. The power train and the lever include holes for passage of a lock shackle to lock the lever in the coupled position. Similarly, the lever and the protruding member of motor operating mechanism also include holes for the passage of a lock shackle to lock the power train in fixed, decoupled positions corresponding to opened and closed positions.
While these arrangements are generally suitable for their intended purposes, it is always desirable to provide a decoupling arrangement having simplified construction and operation that effectively transmits movement of the drive source to the power train in the coupled position and that provides improved structural features for permitting decoupling only at a predetermined position of the power train while restraining the power train against movement in the decoupled position. For example, the decoupling arrangements of U.S. Pat. Nos. 3,508,179 and 4,107,486 utilize a selector handle 38 that is remote from the remainder of the decoupling arrangement and that is connected to the power train via a number of interconnected parts. That arrangement also utilizes a brake mechanism additional to the decoupling arrangement for restraining movement of the power train in the decoupled position. Accordingly, it would be desirable to eliminate the remote location of the selector handle, the parts interconnecting the selector handle, and the additional brake mechanism. Considering the decoupling arrangement of U.S. Pat. Nos. 4,351,994 and the Moto-Draulic switch operator, it would be desirable to simplify the decoupling operation regarding the alignment of an appropriate tool and the unthreading of a bolt. It would also be desirable to reduce the decoupling time. In addition to the convenience of a faster decoupling arrangement, a rapid-acting, simple-to-operate decoupling arrangement also avoids the problem of being in a partially-decoupled phase when an operator is activated remotely. As to the decoupling arrangements of U.S. Pat. No. 4,190,755 and the Delta Star switch operating mechanism, it would be desirable to provide a decoupling arrangement that does not require axial movement of one or more portions of the power train or drive source connections. Although the decoupling arrangements of the Siemens-Allis Type CM-4A motor operating mechanism and the I-T-E Imperial Corporation MO-10 motor operator provide generally compact structures that are relatively simple to operate, it would be desirable to provide a decoupling arrangement that does not require a pin separate from the pivotal coupling bar as in the MO-10 motor operator and that is simpler to operate and provides a more direct indication of the coupling mode than the Siemens-Allis CM-4A motor operating mechanism. Further, the Delta Star switch operating mechanism, the CM-4A motor operating mechanism and the MO-10 motor operator are each capable of being decoupled at any position which can lead to various undesirable results.